Technical Field
The present disclosure relates to an intermediate transfer belt for use in electrophotography.
Description of the Related Art
In an electrophotographic image forming apparatus, for the purpose of reliably obtaining high quality image, a toner image is formed on an intermediate transfer belt to establish a standard of toner concentration. Imaging conditions, such as developing condition, are controlled in accordance with the detected toner concentration. The toner concentration is detected by emitting light from light emitting diode or the like to the toner image portion and the surface of the intermediate transfer belt, and detecting a difference in reflective light quantity between the toner image portion and the surface of the intermediate transfer belt. The greater the reflective light quantity from the intermediate transfer belt, the greater the dynamic range with respect to detection of the toner image and the better detection accuracy. Accordingly, the intermediate transfer belt is required to have a high degree of surface glossiness.
Materials usable for the intermediate transfer belt include thermosetting resins, such as polyimide, and thermoplastic resins, such as polyetheretherketone (PEEK) and polyvinylidene difluoride (PVDF). Because of being high in unit price and poor in processability and productivity, polyimide adversely raises component cost.
On the other hand, thermoplastic resins are low in unit price and easily moldable by extrusion, which is advantageous. In extrusion molding of thermoplastic resins, melt viscosity of the resin and surface roughness of a mold in use have a great influence on the surface roughness, as well as glossiness, of the molded belt. It is already known that the molded belt can be more improved in glossiness by post-processing, such as polishing with a polishing film for forming a mirror surface or formation of a coating layer on its surface.
However, such post-processing for enhancing the glossiness adversely increases the number of processing steps and raises component cost to the level of polyimide without taking advantage of low-cost thermoplastic resins.